// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/sync/engine/net/server_connection_manager.h"

#include <errno.h>

#include <ostream>

#include "base/check_is_test.h"
#include "base/feature_list.h"
#include "base/metrics/histogram.h"
#include "base/observer_list.h"
#include "build/build_config.h"
#include "components/sync/base/features.h"
#include "components/sync/engine/cancelation_signal.h"
#include "components/sync/engine/net/url_translator.h"
#include "components/sync/engine/syncer.h"
#include "net/http/http_status_code.h"
#include "url/gurl.h"

namespace syncer {
namespace {

#define ENUM_CASE(x)    \
  case HttpResponse::x: \
    return #x;          \
    break

const char* GetServerConnectionCodeString(
    HttpResponse::ServerConnectionCode code) {
  switch (code) {
    ENUM_CASE(NONE);
    ENUM_CASE(CONNECTION_UNAVAILABLE);
    ENUM_CASE(SYNC_SERVER_ERROR);
    ENUM_CASE(SYNC_AUTH_ERROR);
    ENUM_CASE(SERVER_CONNECTION_OK);
  }
  NOTREACHED();
}

#undef ENUM_CASE

}  // namespace

HttpResponse::HttpResponse()
    : server_status(NONE),
      net_error_code(-1),
      http_status_code(-1),
      content_length(-1) {}

// static
HttpResponse HttpResponse::Uninitialized() {
  return HttpResponse();
}

// static
HttpResponse HttpResponse::ForNetError(int net_error_code) {
  HttpResponse response;
  response.server_status = CONNECTION_UNAVAILABLE;
  response.net_error_code = net_error_code;
  return response;
}

// static
HttpResponse HttpResponse::ForUnspecifiedError() {
  HttpResponse response;
  response.server_status = CONNECTION_UNAVAILABLE;
  return response;
}

// static
HttpResponse HttpResponse::ForHttpStatusCode(int http_status_code) {
  HttpResponse response;
  if (http_status_code == net::HTTP_OK) {
    response.server_status = SERVER_CONNECTION_OK;
  } else if (http_status_code == net::HTTP_UNAUTHORIZED) {
    response.server_status = SYNC_AUTH_ERROR;
  } else {
    response.server_status = SYNC_SERVER_ERROR;
  }
  response.http_status_code = http_status_code;
  return response;
}

// static
HttpResponse HttpResponse::ForSuccessForTest() {
  CHECK_IS_TEST();
  HttpResponse response;
  response.server_status = SERVER_CONNECTION_OK;
  response.http_status_code = net::HTTP_OK;
  return response;
}

ServerConnectionManager::ServerConnectionManager()
    : server_response_(HttpResponse::Uninitialized()) {}

ServerConnectionManager::~ServerConnectionManager() = default;

bool ServerConnectionManager::SetAccessTokenInfo(
    const signin::AccessTokenInfo& access_token_info) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  CHECK(!base::FeatureList::IsEnabled(kSyncUsePropagatedAccessToken));

  cached_access_token_info_ = access_token_info;
  if (IsAccessTokenInfoValid(cached_access_token_info_)) {
    return true;
  }

  ClearCachedAccessToken();

  // The token was probably expired. Notify sync frontend again to request new
  // token, otherwise backend will stay in SYNC_AUTH_ERROR state while frontend
  // thinks everything is fine and takes no actions.
  SetServerResponse(HttpResponse::ForHttpStatusCode(net::HTTP_UNAUTHORIZED));
  return false;
}

bool ServerConnectionManager::HasCachedAccessToken() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  CHECK(!base::FeatureList::IsEnabled(kSyncUsePropagatedAccessToken));
  return !cached_access_token_info_.token.empty();
}

void ServerConnectionManager::ClearCachedAccessToken() {
  cached_access_token_info_ = signin::AccessTokenInfo();
}

// static
bool ServerConnectionManager::IsAccessTokenInfoValid(
    const signin::AccessTokenInfo& access_token_info) {
  if (access_token_info.token.empty()) {
    return false;
  }

  // Assume the token is valid if the expiration time is not set or the
  // validation feature is disabled.
  if (access_token_info.expiration_time.is_null() ||
      !base::FeatureList::IsEnabled(kSyncValidateAccessToken)) {
    return true;
  }

  return access_token_info.expiration_time > base::Time::Now();
}

void ServerConnectionManager::SetServerResponse(
    const HttpResponse& server_response) {
  // Notify only if the server status changed, except for SYNC_AUTH_ERROR: In
  // that case, always notify in order to poke observers to do something about
  // it.
  bool notify =
      (server_response.server_status == HttpResponse::SYNC_AUTH_ERROR ||
       server_response_.server_status != server_response.server_status);
  server_response_ = server_response;
  if (notify) {
    NotifyStatusChanged();
  }
}

void ServerConnectionManager::NotifyStatusChanged() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  for (ServerConnectionEventListener& observer : listeners_) {
    observer.OnServerConnectionEvent(
        ServerConnectionEvent(server_response_.server_status));
  }
}

HttpResponse ServerConnectionManager::PostBufferWithAccessToken(
    const std::string& buffer_in,
    std::string* buffer_out,
    const signin::AccessTokenInfo& access_token_info) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  HttpResponse http_response =
      PostBuffer(buffer_in, buffer_out, access_token_info);
  SetServerResponse(http_response);
  return server_response_;
}

HttpResponse ServerConnectionManager::PostBufferWithCachedAuth(
    const std::string& buffer_in,
    std::string* buffer_out) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  CHECK(!base::FeatureList::IsEnabled(kSyncUsePropagatedAccessToken));
  return PostBufferWithAccessToken(buffer_in, buffer_out,
                                   cached_access_token_info_);
}

void ServerConnectionManager::AddListener(
    ServerConnectionEventListener* listener) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  listeners_.AddObserver(listener);
}

void ServerConnectionManager::RemoveListener(
    ServerConnectionEventListener* listener) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  listeners_.RemoveObserver(listener);
}

std::ostream& operator<<(std::ostream& s, const struct HttpResponse& hr) {
  s << " Response Code (bogus on error): " << hr.http_status_code;
  s << " Content-Length (bogus on error): " << hr.content_length;
  s << " Server Status: " << GetServerConnectionCodeString(hr.server_status);
  return s;
}

}  // namespace syncer